The Collisions Into Dust Experiment (COLLIDE) was an experiment designed specifically for microgravity environments to investigate dust production in planetary rings by simulating planetary ring particle collisions at low-velocities. It was originally designed as a Get Away Special (GAS) payload to fly on space shuttle Columbia and successfully flew in April 1998 on STS-90.
COLLIDE’s experiments studied collisions between particles in microgravity to better understand how planets and rings formed. During each COLLIDE experiment, a marble sized sphere was launched into a very fine powder and very low speeds. The impacts were video recorded for post-experiment evaluation.
When collisions are slower than 20 cm/s, the impacting particle sticks to the powder surface. Particles moving at these speeds can easily lead to planetary growth.
Low-Velocity Microgravity Impact Experiments into Simulated Regolith
The COLLIDE-2 experiment utilized the same experimental components that flew on STS-90. The hardware and software were modified using the results from COLLIDE in order to further characterize the amount and velocity of ejecta as a function of impact velocity and energy. COLLIDE-2 successfully flew in 2001 on space shuttle Endeavor (STS-108). COLLIDE and COLLIDE-2 consisted of five (5) major systems: the Primary Structure, the Impactor Box System, the Video Camcorder System, Batteries, and the Power and Logic System. Six (6) independent Impactor Box Systems (IBS’s) were implemented in these experiments and were controlled by a single logic unit and powered by a redundant set of batteries.
Low velocity impacts into dust: results from the COLLIDE-2 microgravity experiment
COLLisions Into Dust Experiment 3
COLLIDE-3 is a Suborbital Experiment that consists of one (1) Impactor Box System (IBS) contained within an aluminum vacuum chamber, a video recording system, and a logic unit. These components are all mounted to an aluminum baseplate. The experiment is performed with pre-determined impact parameters (target material, impactor mass, and impactor velocity). The experiment is fully automated using an accelerometer and an internal timed circuitry system.
The IBS consists of a launcher system, a target tray, and a lighting system (shown on the left). A spherical impactor is propelled at low-speeds into a regolith reservoir via a spring-loaded launcher activated by a shape-memory-alloy system. The target tray, orreservoir, is rectangular in shape with dimensions of approximately 11.5 cm x 10.6 cm x 1.9 cm. The tray is filled with granular material (JSC-1, lunar regolith) prior to impactor launch. The JSC-1 is held in place by a mechanical, sliding door until the experiment is ready to be operated in reduced-gravity conditions. The door consists of Teflon pins that run through door guides and is opened and closed with a digital linear actuator (stepper motor). An aluminum vacuum chamber was created for this experiment having dimensions of 30.5 cm x 19.1 x 18.7 cm. The chamber includes 3 ports: electrical, vacuum, and viewing. The electrical port houses an electrical feedthrough through which the circuitry logic unit is connected to the IBS. An o-ring face seal is threaded into the vacuum port along with a stainless steel ball valve attached for air removal and to seal the chamber after vacuum pumping. To video record the experiment, a BK7 optical glass viewport was installed.
Video data is recorded through the viewing porthole using a Prosilica GE 1050 GigE Vision Camera by Allied Vision Technologies. This camera has a pixel resolution of 1024 x 1024 and is capable of recording at 59 frames per second. A flat mirror mounted inside the IBS provides an orthogonal view of the impact. Illumination of the target area is provided by an internal array of LEDs.